Neurotoxic Shellfish Poisoning

Causative organism: Karenia brevis

Toxins produced: Brevetoxins

Neurotoxic Shellfish Poisoning (NSP) produces an intoxication syndrome nearly identical to that of ciguatera in which gastrointestinal and neurological symptoms predominate. In addition, formation of toxic aerosols by wave action can produce respiratory asthma-like symptoms. No deaths have been reported and the syndrome is less severe than ciguatera, but nevertheless debilitating. Unlike ciguatera, recovery is generally complete in a few days. Monitoring programs (based on K. brevis cell counts) generally suffice for preventing human intoxication, except when officials are caught off-guard in previously unaffected areas.

U.S. Finfish, Shellfish and Wildlife Affected by NSP

Harmful Algal Species

Geographic Area

Affected Organisms*

Karenia brevis

Gulf of Mexico
South Atlantic Bight

Bay scallops, surf clams, oysters, southern quahogs, coquinas

Turnicates

Many commercial and recreational species of fish, sea birds+, sea turtles, manatees+, dolphins

*Found to contain algal toxins, or to be adversely affected by toxic or harmful marine algae.+Causative algae implicated, not confirmed.